Spin Current Sensing for Selective Detection of Explosive Molecules

Spin current based sensing methods offer a new approach to the development of selective detection devices for explosive molecules. Employing a combination of bias voltages and transverse electric fields to vary the chemiresistive properties of a zigzag graphene nanoribbon, dual-input dual-output sensors of this kind offer major advantages: tuning the electrical properties of a single nanoribbon is equivalent to deploying a sensor array, and measuring two outputs (spin-up and spin-down currents, total current and spin current difference, etc.) offers improved selectivity. Ab initio modeling suggests that the magnetic properties of the analyte, charge transfer effects, current transmission pathways, and analyte molecule size all influence sensor signatures. Analysis of the sensing cause-effect physics relies upon the calculation of energy averaged bond currents, which visualize the global spin current transport. Principal component analysis of the proposed sensing scheme suggests that it can distinguish between common background gases, nitroaromatic explosives, and nitramine explosives and will offer far better selectivity than carbon nanotube based explosive sensing devices.